I was looking at Crawfishboxes, the SBN Astros site, and I was turned on to a really cool site:

http://www.fangraphs.com/

They do win expectancy charts for every game, and compile stats for every player as well. For the year, the top Rangers hitters this season in terms of WPA are:

Michael Young 119.8%
Hank Blalock 87.9 %
Kevin Mench 77.7 %
Mark DeRosa 68.9 %
Gary Matthews Jr. 43.9 %

Barajas is at the bottom

The top Rangers starters are:

Kameron Loe 30.3 %
Kevin Millwood 22.1 %
John Koronka 20.2 %
Rick Bauer 18.8 %
Robinson Tejeda 7.6 %

RA is at the bottom

The top relievers are:

Akinori Otsuka 62.6 %
Antonio Alfonseca 39.7 %
Joaquin Benoit 25.1 %
Rick Bauer 20.0 %
Ron Mahay 5.0 %

Coco is at the bottom

I assume the season stats are the sum of every WPA for every game for the year.

Also, especially for Chris, the site has an article explaining WPA, or Win Probability Added:

http://www.hardballtimes.com/main/article/the-one-about-win-probability/

Interesting stuff.